maropu commented on a change in pull request #28151: [SPARK-31383][SQL][DOC]
Clean up the SQL documents in docs/sql-ref*
URL: https://github.com/apache/spark/pull/28151#discussion_r405880362
##########
File path: docs/sql-ref-syntax-qry-select-setops.md
##########
@@ -19,161 +19,178 @@ license: |
limitations under the License.
---
+### Description
+
Set operators are used to combine two input relations into a single one. Spark
SQL supports three types of set operators:
-- `EXCEPT` or `MINUS`
-- `INTERSECT`
-- `UNION`
+
+ - `EXCEPT` or `MINUS`
+ - `INTERSECT`
+ - `UNION`
Note that input relations must have the same number of columns and compatible
data types for the respective columns.
### EXCEPT
+
`EXCEPT` and `EXCEPT ALL` return the rows that are found in one relation but
not the other. `EXCEPT` (alternatively, `EXCEPT DISTINCT`) takes only distinct
rows while `EXCEPT ALL` does not remove duplicates from the result rows. Note
that `MINUS` is an alias for `EXCEPT`.
#### Syntax
+
{% highlight sql %}
[ ( ] relation [ ) ] EXCEPT | MINUS [ ALL | DISTINCT ] [ ( ] relation [ ) ]
{% endhighlight %}
-### INTERSECT
-`INTERSECT` and `INTERSECT ALL` return the rows that are found in both
relations. `INTERSECT` (alternatively, `INTERSECT DISTINCT`) takes only
distinct rows while `INTERSECT ALL` does not remove duplicates from the result
rows.
+#### Examples
-#### Syntax
{% highlight sql %}
-[ ( ] relation [ ) ] INTERSECT [ ALL | DISTINCT ] [ ( ] relation [ ) ]
-{% endhighlight %}
-
-### UNION
-`UNION` and `UNION ALL` return the rows that are found in either relation.
`UNION` (alternatively, `UNION DISTINCT`) takes only distinct rows while `UNION
ALL` does not remove duplicates from the result rows.
-
-#### Syntax
-{% highlight sql %}
-[ ( ] relation [ ) ] UNION [ ALL | DISTINCT ] [ ( ] relation [ ) ]
-{% endhighlight %}
-
-### Examples
-{% highlight sql %}
--- Use number1 and number2 tables to demonstrate set operators.
+-- Use number1 and number2 tables to demonstrate set operators in this page.
SELECT * FROM number1;
-+---+
-| c|
-+---+
-| 3|
-| 1|
-| 2|
-| 2|
-| 3|
-| 4|
-+---+
-
+ +---+
+ | c|
+ +---+
+ | 3|
+ | 1|
+ | 2|
+ | 2|
+ | 3|
+ | 4|
+ +---+
+
SELECT * FROM number2;
-+---+
-| c|
-+---+
-| 5|
-| 1|
-| 2|
-| 2|
-+---+
+ +---+
+ | c|
+ +---+
+ | 5|
+ | 1|
+ | 2|
+ | 2|
+ +---+
SELECT c FROM number1 EXCEPT SELECT c FROM number2;
-+---+
-| c|
-+---+
-| 3|
-| 4|
-+---+
+ +---+
+ | c|
+ +---+
+ | 3|
+ | 4|
+ +---+
SELECT c FROM number1 MINUS SELECT c FROM number2;
-+---+
-| c|
-+---+
-| 3|
-| 4|
-+---+
+ +---+
+ | c|
+ +---+
+ | 3|
+ | 4|
+ +---+
SELECT c FROM number1 EXCEPT ALL (SELECT c FROM number2);
-+---+
-| c|
-+---+
-| 3|
-| 3|
-| 4|
-+---+
+ +---+
+ | c|
+ +---+
+ | 3|
+ | 3|
+ | 4|
+ +---+
SELECT c FROM number1 MINUS ALL (SELECT c FROM number2);
-+---+
-| c|
-+---+
-| 3|
-| 3|
-| 4|
-+---+
+ +---+
+ | c|
+ +---+
+ | 3|
+ | 3|
+ | 4|
+ +---+
+{% endhighlight %}
+### INTERSECT
+
+`INTERSECT` and `INTERSECT ALL` return the rows that are found in both
relations. `INTERSECT` (alternatively, `INTERSECT DISTINCT`) takes only
distinct rows while `INTERSECT ALL` does not remove duplicates from the result
rows.
+
+#### Syntax
+
+{% highlight sql %}
+[ ( ] relation [ ) ] INTERSECT [ ALL | DISTINCT ] [ ( ] relation [ ) ]
+{% endhighlight %}
+
+#### Examples
+
+{% highlight sql %}
Review comment:
@huaxingao I moved the examples into the seb-sections of
`EXCEPT/INTERSECT/UNION` for readability. Could you check this?
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